1.2.12 Define the term Usability
1.2.13 Identify a range of usability problems with commonly used digital devices.
1.2.14 Identify methods that can be used to improve the accessibility of systems.
1.2.15 Identify a range of usability problems that can occur in a system.
Usability means making the computer systems easy to use, matching them more closely to user needs and requirements
it is a measure of how easy it is to use a product to perform prescribed tasks.
It is a subset of ergonomics and focuses on the ease of use and learnability of human interactions with the system.
Usability puts the user, rather than the system, at the center of the process.
This process is called user-centered design and incorporates user concerns at the beginning of the design process.
Usability design considers who the users are, what they know and how they learn, the context in which they use a system, whether users accomplish the tasks at a desired speed, training required to use the program, and supporting materials available to help users.
Early focus: On the user and the task--the design team should be in direct contact with users.
Iterative design: Based on a cyclic process of prototyping, testing, analyzing and refining the system.
Empirical measurement: Tests the system early on, and test the system on real users using behavioral measurements.
Ergonomics is the scientific discipline concerned with the understanding of human interactions among humans and other elements of a system.
Applies theory, principles and data to the design process in order to optimize human well-being and system performance.
There are three main categories of ergonomics:
Concerns the human body’s responses to physical and physiological work demands.
Repetitive strain injuries from repetition, vibration, force and posture are the most common types of issues and thus have design implications.
E.g. designing a lifting job to occur at waist height, selecting a tool shape that reduces awkward postures, etc.
Focuses on the fit between human cognitive abilities with its limitations and the machine, task and environment.
E.g. designing a software interface to be “easy to use”, designing a sign so that the majority of people will understand and act in its intended manner, etc.
Deals with the optimization of systems.
Includes communication, work design, shift (work hours) management, crew resource management, teamwork, virtual organizations, telework and quality management.
General issues with input.
Reliability of voice recognition.
Real or virtual keyboards.
Touch screen systems.
General issues with output.
General usability of receiving outputs.
Display/screen and its accompanying text.
Layout and contrast of screen.
Quality of audio feedback.
Clarity and intonation of speech of audio feedback (TTS).
Quality of physical output.
Online ticketing systems cause popular events to sell out quickly, which prevents everyone from getting a fair chance to buy tickets.
During online purchasing, tickets are only guaranteed for a short time until completion of the booking process.
This pressure may cause users to make rushed decisions with regards to seating and other options.
Speculators may buy blocks of tickets, limiting access to desired areas and increases the cost.
May provide more functionality than is required, causing frustration to the user who simply wants to check their payroll.
There may be financial terms and acronyms used in the system that are unrecognizable to the user.
Having to be online might create privacy concerns for a user, particularly on shared computers.
Users experiencing problems using the system may not feel comfortable discussing their financial matters with strangers through a helpdesk.
Can create optimized schedules for organization, but often ignore human factors and workplace realities.
They may not take into account issues such as locations, travel times, fatigue, resource allocation e.g. projectors, network capabilities and personal commitments.
Computers are based off of formal logic while human language is flexible, dynamic, ambiguous and do not assign fixed meanings.
The way someone says a word depends on age, gender, geographic dialect, the particular anatomy of one’s vocal tract, how quickly or formally they are speaking.
Users may not want to speak about important or sensitive information in a public space. If a person speaks in a lower volume or in a loud area, the system may not be able to hear the user’s inputs.
Sometimes voice recognition picks up commands from unrelated speech, causing undesired behavior by a digital device.
Automated systems for users are used to enable organizations to gather data on the success of a system.
This data can be used in the iterative design to improve the functionality and usability of the system.
Systems to provide feedback are common in education, business and other organizations.
Users may not respond to the types of questions asked on a survey.
Users might not understand technical terms in the system of feedback.
Users might not be provided with the opportunity to provide open-ended feedback.
The system of providing feedback might be too time-consuming for users, preventing them from completing it.
Accessibility (accessible computing) refers to the availability of a system to all people, regardless of disability or severity of impairment.
Occurs when software, hardware or a combination of both is used to enable use of a system by a person with a disability or impairment.
Is also known as assistive technology.
Usability
If the OS is too complex then users may have issues navigating through the system.
If the hardware is too complex e.g. too many buttons, users may have issues using the computer system.
Can peripheral devices be attached and removed with ease?
Accessibility
If the user has to migrate to a new location, they might find it hard to disassemble and reassemble the system in their new location.
Users with conditions such as Parkinson’s Disease may be unable to type keyboards and use mouses properly.
Physical limitations--if the users don’t have arms or hands, they would need compatible assistive input devices.
Usability
If the OS is too complex then users may have issues navigating through the system.
If the hardware interface is too complex e.g. too many buttons, users may have issues using the computing system.
If the user is outdoors in the sun, the screen brightness must be high to be visible.
The mobile device must fit in one’s hand comfortably and should not slip.
Short battery life may mean the user has to use it sparingly and thus are unable to achieve full utilization.
Accessibility
If the user has bad eyesight, they might find it hard to see the screen if it is too small and if the text is too small in size.
If the user has certain health issues and limited hand mobility i.e. through arthritis, the user input method may pose various issues.
Error-prone gestures--a multitude of complicated gestures on a multi-touch screen are difficult to perform by users who do not possess fine motor control.
If the user has poor hearing then it would be hard to use a mobile device with low speaker volumes.
Accessibility can be improved by a variety of interfaces, input techniques and output methods.
Voice recognition software.
Allows users to speak into a microphone and software on the computer translated the voice to text.
Text-to-speech.
Converts normal language text into speech.
Allows environmental barriers to be removed for people with a wide range of disabilities, bringing the product to a wider audience.
Color and font changes.
A system should offer the ability to change the font size and offer high contrast color schemes for the visually impaired.
Touch screen.
Enables the user to interact directly with what is displayed, rather than using a mouse, touchpad, or any other intermediate devices.
Braille keyboard.
Increases the accessibility of computer systems for those who are visually impaired.
Sip and puff.
Ideal for people who have limited or no motor capability to operate switch activated devices.
Works with wheelchair navigation and for people with severe motor disabilities.
Trackball.
People with a mobility impairment use this as an assistive technology.
Braille displays.
Is an electronic device that connects to a computer to display braille characters.
Is used to represent a line of text on a computer screen.
Light signaler alerts.
Monitors computer sounds and alerts the computer user with light signals.
Is useful when a user cannot hear computer sounds or is not directly in front of the computer screen.